Anatomical complexities for root canal

Question 1

How many root canals do upper anterior teeth typically have?

Answer 1

One

Question 2

How many root canals do upper 4s have and where are they?

Answer 2

2 - buccal and palatal

Question 3

How many root canals do upper 5s have?

Answer 3

One

Question 4

How many root canals do upper 6s typically have and where are they?

Answer 4

4, MB1, MB2, P, D

Question 5

How many root canals do upper 7s usually have?

Answer 5

3

Question 6

How many root canals do lower anterior teeth have typically?

Answer 6

One

Question 7

How many root canals do lower premolars typically have?

Answer 7

One

Question 8

How many root canals do lower molars have typically?

Answer 8

3

Question 9

What overall shape is the pulp generally?

Answer 9

Oval

Question 10

Irregular anatomy of lower incisors

Answer 10

Up to 41% have a second lingual canal

Question 11

Irregular anatomy of lower 4s

Answer 11

25% have 2 canals, 0.5% have three canals

Question 12

Irregular anatomy of upper 4s

Answer 12

6% have three canals

Question 13

Irregular anatomy of upper second premolars

Answer 13

40% have a single root canal, 58% have 2 canals

Question 14

Irregular anatomy of upper 6s

Answer 14

91% have MB2 and 72% have a separate apical foramen

Question 15

What is the prevalence of c shaped canals?

Answer 15

1% of lower 6s, 3% of lower 7s, increases to 30-42% in Korean populations

Question 16

What is Ahmed et al’s classification of root canal anatomy?

Answer 16

NTNO-C-F where N is number of roots, TN is tooth number (FDI), O is orifice, C is canal and F is foramen

Question 17

What do we use to assess curvature of the roots?

Answer 17

Schneider angle

Question 18

How to calculate the Schneider angle?

Answer 18

Draw a line parallel to the long axis of the tooth in the coronal third. Draw a line from the apical foramen to intersect the first line. The angle formed is Schneider angle.

Question 19

What Schneider angle indicates an I form canal curvature?

Answer 19

Less than 10°

Question 20

What Schneider angle indicates a J form canal curvature?

Answer 20

10-30°

Question 21

What Schneider angle indicates a C or S shaped canal curvature?

Answer 21

Over 30°

Question 22

What are c shaped canals?

Answer 22

Cross sectional shape similar to the letter c in which there is a single c shaped root or where Mesial and distal canals communicate (or remain separate) due to fusion of the mesial and distal roots.

Question 23

Which teeth are more prone to c shaped canals?

Answer 23

Lower 7s

Question 24

What is concrescence?

Answer 24

Fusion of roots of at least two teeth by cementum

Question 25

What is dens evaginatus?

Answer 25

Developmental anomaly resulting in the formation of an accessory or talon cusp

Question 26

What is dens invagination?

Answer 26

Developmental anomaly that results in an invagination of the enamel organ into the dental papilla prior to the calcification of the dental tissues

Question 27

What is an enamel pearl?

Answer 27

A focal mass of enamel located apical to the cementoenamel junction.

Question 28

What is gemination?

Answer 28

“Twinning”; when a single tooth germ attempts to divide, resulting in the incomplete formation of two teeth; the tooth usually has a single root and root canal.

Question 29

What is a palatal gingival groove?

Answer 29

Developmental anomaly that is usually found on the palatal aspect of the root of a maxillary incisor tooth. Usually extends over cingulum and extends down onto the root surface.

Question 30

What is tooth fusion?

Answer 30

Double tooth due to the union of two adjacent tooth germs

Question 31

What is root dilaceration?

Answer 31

Deformity characterised by displacement of the root of a tooth from its normal alignment with the crown. May occur due to injury during tooth development.

Question 32

What is radix entomolaris / paramolaris?

Answer 32

Supernumerary root in a mandibular molar, usually located distolingually (entomolaris) or mesiobucally (paramolaris)

Question 33

What is taurodontism?

Answer 33

Change in tooth shape due to failure of Hertwig’s epithelial root sheath to invaginate at the correct horizontal level. Enlarged pulp chamber, apical displacement of pulpal floor, no constriction at the level of the CEJ.

Question 34

What are the laws of endodontic access?

Answer 34

Centrality, concentricity, colour change, orifice location (2), symmetry (2)

Question 35

What is the law of centrality for endodontic access?

Answer 35

The pulp chamber of every tooth lies in the centre of the tooth at the level of the CEJ.

Question 36

What is the law of concentricity for endodontic access?

Answer 36

The walls of the pulp chamber are concentric to the external outline of the tooth at the level of the CEJ.

Question 37

What is the law of colour change for endodontic access?

Answer 37

The colour of the pulp chamber is darker than the surrounding walls.

Question 38

What are the two laws of orifice location for endodontic access?

Answer 38

Orifices of the root canals are always located at the junction of the walls and floor. The orifices of root canals are located at the ventrices of the floor-wall junction.

Question 39

What are the two laws of symmetry for endodontic access?

Answer 39

Excluding maxillary molars, canal orifices are equidistant from a line drawn in a mesial distal direction through the centre of the pulp chamber floor. Excluding maxillary molars, the canal orifices lie on a line perpendicular to a line drawn in a mesial distal direction through the centre of the pulp chamber floor.

Question 40

Give three different types of endodontic access cavities.

Answer 40

Ninja, conservative, traditional

Question 41

Which teeth have MB2?

Answer 41

Upper molars, 6s more frequently than 7s

Question 42

How to find MB2?

Answer 42

It is often covered by a shelf of dentine so remove dentine carefully along a line from MB1 to the palatal canal.